Telephone-exchanore system



Patented July 15, 1924.

UNITED STATES l,5tl,t

PATENT OFFICE.

ALBEN E. LUNDE LL AND EDGAR H. CLARK, OF NEW YORK, N. Y., ASSIGNO'RS TO WEST- ERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OI" YORK.

'IELEPI-IONE-EXGHANG-E SYSTEM.

Application filed April 28, 1920.

To all 2071.072?) it vimg concern:

Be it known that we, Annnn E. LUnnnLL and EDGAR ll. CLARK, citizens of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain. new and useful Improvements in. T'elephoneldxchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems of the semi-automatic type, and more particularly to the type employing a B operator for extending aconnection semiautomatically from an originating operatofis position to a terminating operator s position.

Specifically the invention relates to inn provenients in the circuits at the position of the terminating operator of a system of the typ employing a call indicator at the terminating operators position which adapted to be set by a B operator at a distant otlice over the trunk line extending betweei i the two offices. 7

It is the object of this invention "to provide circuits at a terminating operators po-- sition whereby calls which are extended thereto may on further extended in a rapid and efficient manner.

One feature of the invention resides in the provision of means for lighting an as signmei it lamp at the 'tern'iinating opcra t rs position, corresponding to an idle cord circuit of th position which has been seized by an otlice selector having access thereto, re 'ardlr-ss of whether the calling the s d cord circuit is down, or through the negligence orpreoccupation or"? the op.- erator has been left up in a jack.

A further feature of the invention resides in the provision. or means for preventing the terminating operator from assigning the incoming call to a call-indicating device at her position until after the calling plug of the cord circuit over which the call is incoming, has been taken down from the jack over which the preceding i-ncoming call over this cord circuit was estended.

A still further feature resides in the pro Vision. of an assignment key which is of the non-locking type and which, upon being manipulated, closes an.v initial energizing circuit for an. assignment relay which therupon locks up.

' plug or Serial No. 377,215.

The improved circuits of the terminating operators position are designed to be substituted tor the corresponding circuits disclosed in Figure 5 of the Patent No. 1,342,823)- issued to Alben E. Lundell and Edgar Clark, June 8, 1920. Inasmuch as the invention does not directly involve the remaining circuits of the complete system as disclosed in said patent, it is not deemed necessary to an understanding of the invention to show the entire circuits necessary for extending a call from the line of a calling subscriber to and through the circuits at the terminating operators position to the line of'the desired subscriber, ant therefore only so much of the circuits as are required to fully disclose the improved features of this invention have been dis closed.

The accompanying drawing shows one embodiment of the genus of the invention, in which one cord clrcuit of a terminating operators position O is disclosed, together with the lamp signals and assignment key appertaining to such cord circuit, and one subscribers line terminating before the po sition of the operator.

The manner in which the circuits of the terminating operators position are organized will best be presented in connection with a description of the mode of their operation. It will be assumed that the connection has been extended to the idle cord circuit of. the operators position 0 shown in the drawing, by means of apparatus such as is shown in the patent hereinbefore referred to, and it will be further assumed that the plug P of the selected cord circuit, is down or in its normal position.

A; circuit is now established for the relays 2 and 3 of the selected cord circuit which 111 y be traced "from grounded battery of 48 volts potential, through the back contact and lower armature of sleeve relay t through the righthand winding oi the marginal relay 2, the winding of sensitive relay 3, the normally closed right-hand armatu'e contacts of reversing relay 5, through the upper lefthand winding of repeating coil 6, the back contact and upper armature of relay 7, thence over the upper heavy talking strand 8 of the cord circuit, through the switch sand connections by means of which the call has been extended to the cord circuit, over the lower heavy talking strand 9, through the lower armature and back contact of relay 7, the lower left-hand winding of the repeating coil 6, the normally closed lefthand armature contacts of relay 5, thence to ground through the left-hand winding of relay 2. Since the plug P of the selected cord circuit is in normal position and 48 volt battery is connected to the armature of relay 4-, both the marginal relay 2 and the sensitive relay 3 energize in this circuit. Relay 2 closes a circuit for relay 10 which may be traced from grounded battery through relay 10 and thence through the grounded armature and front contact of relay 2. Relay 3 energizes and closes a circuit for relay 11, which extends from grounded battery through the resistance 12, the front contact and armature of relay 3, thence to ground through the winding of the relay 11. Relay 11 does not energize at this time since its winding is short-circuited through the energization of relay 10 by a direct connection to ground at the front contact and right-hand armature of relay 10.

Relay 10, upon energizing, closes at its inner left-hand armature and front contact a shunt around the winding of relay 3, to cause supervision back over the trunk conductors 8 and 9 for purposes well known in the art, and at its outer left-hand armature closes a circuit for the assignment lamp 13, which circuit may be traced from grounded battery through the lamp, right-hand armature and back contact of assignment relay 14, through the inner left-hand armature and back contact of relay 15, and thence to ground through the front contact and outer left-hand armature of relay 10. At its right-hand armature and back contact, relay 10 opens a circuit extending through the right-hand front contact of relay for preventing the closure of a circuit for the dis connect lamp 16 upon the subsequent energization of relay 15, when the operator inserts the plug P of the cord circuit in the jack of the desired line for extending the call.

The operator, upon noting tie illumination of the assignment lamp 13, depresses the assignment key K which is individual to the cord circuit of her position which has been selected. Closure of the contacts of the assignment key establishes a circuit for the assignment relay 14 which may be traced from ground, through the contacts of the key, the right-hand winding of the assignment relay 14, the outer left-hand armature of relay 15 and its back contact, and thence to battery over conductor 17 which leads to the holding relay (not shown) of the call indicator of the operators position for preparing a holding circuit to hold the lamp relays of the indicator in the position in which they are subsequently set by impulses transmitted from the distant otlic-e over the trunk conductors 8 and 9. Relay 14 energizes in this circuit and at its inner lefthand armature and front contact closes a lockii'ig-circuit for itself independent of the contacts of key K, which circuit extends from ground through the inner left-hand armature and front contact and both windings of relay 14, and thence to battery over the circuit previously traced through conductor 17. At its right-hand armature and back contact, relay 14 opens the circuit of the assignment lamp 13, and reconnects the assignment lamp to the interrupter 18 through this armature'and its front contact, for producing a flashing signal which continues until the call-indicator has been entirely set to indicate the number of the desired line. At its outer left-hand armature and front contact, relay 14 closes a circuit for relay 7 which circuit extends from grounded battery, outer left-hand armature and front contact of relay 13, thence to ground through the winding of relay 7. Relay 7 energizes in this circuit and at its armatures and back contacts, disconnects the in coming trunk conductors 8 and 9 from the left-hand windings of the repeating coil 6, and at its armatures and front contacts connects these trunk conductors to the impulse conductors 19 and 20 which lead to the impulse relays of the call-indicator in the manner described in the patent hereinbefore referred to.

As soon as the number of the desired subscriber has been entirely set up on the callindicator, the operator, noting the number indicated, picks up the plug P of the selected cord circuit, and after making the usual test to determine the busy or idle condition of the desired line, inserts the plug in the ack J of the line. Upon the insertion of the plug in the jack, a circuit is established for the sleeve relay 4 and for the relay 15 which may be traced from grounded battery through the Winding of relay 15, through the winding of relay 4, through sleeve contacts of the plug P and the jack J, thence to ground through the Winding of the cut-off relay 21 of the subscribers line. Relays 15, 4 and 21 energize in this circuit. The energization of cut-oif relay 21 disconnects the windings of the subscribers line relay 22 in the usual manner. The energization of sleeve relay 4 cuts off at its upper armature and back contact the connection from the tip of the plug to the testing conductor which leads in the usual manner to the operators head set, and connects the tip of the plug to the upper right-hand winding of the repeating coil 6. At its lower armature and back contact, relay 4 disconnects the source of 48 volt current from the circuit extending through the windings of relays 2 and 3, and substitutes therefor a source of 24 volt current for a purpose to be described hereinafter. The

energization of relay 15 opens at its outer fta arm ture and b c c tact, e circuit which was established. for the assign-. ment relay l4: and the holding relay (not shown) of the call indicator, thereby causing the deenergization of these relays, and at its right-hand ar n ature and front contact closes a circuit for causing the application, ofring. ing current to the subscribers line, At its, inner left-hand armature and back contact, relay 15 opens the initial circuit of the as,- signnient lainp 13 to prevent its reoperation upon the falling back of relay 14;.

At the time relay 7 energized to disconnect the trunk conductors 8 and 9 from the left-hand windings of repeating coil 6,, the cicuit of relay 2' was opened and this relay deenergizcd, but upon the opening of the holding circuit of relay 14. when the op.- erator extends the call to, the desired line, and the consequent deenergization of relay 7, the circuit for relay 2 is again established, thereby causing the energization of relay 10V to hold the circuit of disconnect lamp: 16 open until. the connection is taken down.

The circuit for causing the application of ringing current to the called subscribers line, closed by the energization of relay 15, may be traced through the lamp 16, through the righthand armature and front contact of relay 15, the back contact and armature of the ringing cut-off relay 23, the back contact and left-hand armature of relay 24, and thence to ground through the ringing relay 25. Relay 25, energizes. in this circuit and at its arinatures and back contacts opens the talking conductors of the cord circuit extending from the right-hand windings of the. repeating coil 61 to the tip and ring contacts of the plug P, and at its armatures and front contacts connects asource of ringing current to the line 01" the called subscriber, which circuit may be traced: from the source of ringing current through the winding of relay 23, front contact and lower armature of relay through the ring contacts of plug P and jack J, over one limb of the subscribers line, through the ringer 26- and condenser 27 at the subscribers substation,

, over the other limb of the line through the tip contacts of the jack J and plug P, the upper armature and front contact of sleeve relay 4;, and thence to ground through the upper arn'iature and front contact of the ringing relay 2?,

In response to the application of the ringing current, the called subscriber removes his receiver from the switchhook, thereby reducing the resistance of the circuit over which the ringing current is applied, causingthe energization of the ringing cut-oft relay 28: This relay upon energizing, opens at its armature and front contact, the shunt around relay 24, thereby permitting relay 24 to energize. Relay 24 at its left-hand, armature and front contact, now closes a shunt circuit around the wind ing of the ringing relay 25, and locks itself up, to grounded battery at the right-hand armature and front contact of relay 15, The ringing relay 25, upon. being shunted out at, the contacts of relay 24, deenergizes, disconnecting the source of ringing current from the tip and ring contacts of the plug P, and reestablishes the connection from the contacts of the plug to the right-hand windings of the repeating coil 6. The calling supervisory relay 28. is now energized over a circuit extending from grounded battery, through the lower right-hand winding of repeating coil 6, the winding of relay 28, back contact and lower armature of relay 25, the ring contacts of the plug and jack over the subscribers line, back through the tip contacts of the plug and jack, through the upper armature and front contact of relay 4:, the upper armature and back con tact of relay 25, and thence to ground through the upper right-hand winding of repeating coil 6. The calling supervisory relay 28; energizes in thiscircuit and at its armature and front contact closes a circuit for the reversing relay 5, which circuit may be traced from grounded battery through the winding of relay 5, the front contact and armature of relay 28, and thence to ground through the right-hand arn'iature and front contact of relay 24. The energization of relay 5 in this circuit causes the reversal of battery connections to the incoming stands 8 and 9 of the cord circuit, for causing a reversal in the direction of current flow over the trunk circuit leading to the distant originating oifice for the purpose of operating the usual polarized supervisory relay at such o'liice for apprising the operator at such ofiice of the fact that the called subscriber has responded to the call, and that the circuits are in a condition for the carrying on of the desired conversation.

Uponthe termination of the conversation, the called subscriber returns his recciver to its switcl'ihoolr, thereby opening the circuit through the supervisory relay 28, which in turn opens the circuit through the reversing relay 5. The reversing relay 5 deen-ergizes, and at its armature contacts reverses the battery connections to the strands 8 and 9 of the cord circuit for causing a reversal of the direction of current flow over the trunk circuit extending to the distantofli'ce for the purpose of giving a disconnection signal at such oflice. The operator at such distant oiiice, noting the disconnect signal causes the release of the con nection between such office and the strands 8 and 9 of the cord circuit at position 0-, thereby causing the deenergization of relay 2. The deenergi'zation of relay 2 opens the circuit of relay 10, which at its right-hand arn'iature and back contact closes a circuit for the disconnect lamp 16, which circuit may be traced from grounded battery through the lamp 16, through the righthand armature and front contact of relay 15, thence to ground through the back contact and right-hand armature of relay 10. The operator noting the illumination of lamp 16, pulls down the plug P from the jack 5 of the called line, thereby opening the circuit through relays 21, 4 and 15 which thereupon deenergize. The deenergization of relay 21 reconnects the line relay 22 of the called subscriber to the line of the subscriber, and the deenergization of relay 15 opens the circuit of the disconnect lamp 16 and the locking circuit of relay 2 1. The circuits of the cord circuit are now in normal condition.

If, at the time the cord circuit was seized, the plug P, through the negligence or preoccupation of the operator was up in the jack of some line appearing before the operators position, the marginal relay 2 would not have energized in the circuit previously traced, extending over the trunk conductors S and 9, since with the plug P in the jack J, the sleeve relay -it would have been energized, thereby connecting the 21 volt battery into the energizing circuit of relay 2 in the place of the 48 volt battery. The sensitive relay 3 does, however, energize in this circuit since it is so wound that it will attract its armatures when a current of low voltage is connected into the circuit at the armature contacts of the sleeve relay 4. Relay 3, upon energization, closes a circuit for the relay 11, which may be traced from grounded battery through resistance element 12, through the front contact and armature of relay 3, thence to ground through the winding of relay 11. Relay 11. upon energizing, closes a locking circuit for itself extending through its left-hand armature and front contact to grounded battery. At its inner right-hand armature and front contact, relay 11 closes a shunt around the winding of relay 3, and at its outer right hand armature and front contact closes a circuit for the assignment lamp 13, which may be traced from grounded battery through the lamp through the right-hand armature and back contact of relay 1%, thence to ground through the front contact and outer right-hand armature of relay 11. With the winding of relay 3 shunted, sufli cientcurrent now flows through the winding of relay 2 to permit a supervisory condition to be established back over the conductors 8 and 9, but current from the 24:- volt source is not sutlicient to cause the energization of relay 2. Relay 10, therefore, does not energize to place a shunt around the winding of relay 11 and relay 11 remains energized. Since relay 15 is at this time energized in series with relay 1, the circuit of the disconnect lamp 16 is closed. The operator noting the illumination of both the assignment lamp 13 and the disconnect lamp 16 takes down the plug P releasing relays 4 and 15, thereby restoring the cord circuit to its standard calling condition. The 48-volt source of current is now connected into the circuit of relay 2 in place of the 2el-volt source at the back contact of relay 1, and relay 2 now energizes to reoperate the assignment lamp in the standard manner as hereinbefore described. From this point the circuits function in the manner hereinbefore set forth.

From the foregoing description, itwill be apparent that circuits are provided for causing the illumination of the assignment lamp of a selected idle cord circuit, regardless of whether the terminal plug of such cord circuit is down, or up in the jack of some line with which it has previously established a connection; that means is provided for preventing the operation of the assignment relay for connecting the call indicator of the operators position to the incoming strands of the cord circuit until after the plug has been taken down from the jack; and that means has been provided for locking up the assignment relay independently of the assignment key so that a non-locking assignment key may be employed.

What is claimed is:

I. In a telephone exchange system, subscribers lines, a cord circuit terminating in a plug terminal for extending a connection to any one of said lines, a signaling device, and means for operating said signaling device upon the seizure of said cord circuit, irrespective of the position of said plug terminal with relation to the jacks of lines to which it has access.

2. In a telephone exchange system, subscribers lines, a cord circuit terminating in a plug terminal for extending a connection to any one of said lines, a signaling device, means for operating said signaling device upon the seizure of said cord circuit, a second signaling device, and means for operating both of said devices if said plug terminal is in the jack of a line to which it has access at the time said cord circuit is seized.

3. In a telephone exchange system, subscribers lines, a cord circuit for extending a connection to any one of said lines, a signaling device, means operated upon the seizure of said cord circuit for operating said device, means effective upon the response of the operator for operating said device in a distinctive manner, and means effective upon the extension of said circuit to a subscribers line for cutting off said signaling device from operation.

4. In a telephone exchange system, subscribers lines, a cord circuit for extending a connection to any one of said lines, a signal lamp, means operated over the incoming end of said cord circuit upon the seizure thereof for causing the illumination of said lamp, means effective upon the response of the operator for causing the illumination of said lamp in a distinctive manner, and means operated upon the extension of said circuit to a subscribers line for extinguishing said lamp.

5. In a telephone exchange system, subscribers lines, a cord circuit for extending a connection to any one of said lines, a signal lamp, means operated over the incoming end of said cord circuit upon the seizure thereof for causing the illumination of said lamp, means effective upon the response of the operator for flashing said lamp, and means operated upon the extension of said cord circuit to a subscribers line for extinguishing said lamp.

6. In a telephone exchange system, subscribers lines, a cord circuit terminating in aplug terminal for extending a connection to any one of said lines, a signal lamp, means for illuminating said lamp upon the seizure of said cord circuit irrespective of the position of said plug terminal with relation to the jacks 01. the lines to which it has access, means effective upon the response of the operator for causing the illumination of said lamp in a distinctive manner, and means operated upon the extension of said cord circuit to the desired subscribers line for extinguishing said lamp.

7. In a telephone exchange system, subscribers lines, a cord circuit terminating in a plug terminal for extending a connection to any one of said lines, an assignment lamp, and a pair of relays adapted to be energized over the incoming end of said cord circuit upon the seizure of said circuit, each eftective for causing the illumination of said lamp, one of said relays being responsive irrespective of the position of said plug terminal with relation to the jacks of lines to which it has access and the other of said relays being responsive only when said plug terminal is down or disconnected from one of said jacks.

8. In a telephone exchange system, subscribers lines, a cord circuit terminating in a plug terminal for extending a connection to any one of said lines, a relay operated upon the insertion of said plug in the jack of a subscribers line, an assignment lamp, and a pair of relays adapted to be energized over the incoming end of said cord circuit upon seizure of said circuit, each upon energization efl ective for causing the illumination of said lamp, one of said pair of relays being responsive only when said first relay is deenergized.

9. In a telephone exchange system, subscribers lines, a cord circuit terminating in a plug terminal for extending a connection to any one of said lines, a sleeve relay operated upon the insertion of said plug in the jack of a subscribers line, an assignment lamp, and a pair of relays adapted to be energized in a circuit extending over the incoming end of said cord circuit and through the contacts of said first relay effective for causing the illumination of said lamp, one of said pair of relays responsive only when said first relay is deenergized.

10. In a telephone exchange system, subscribers lines, a cord circuit termina ing in a plug terminal for extending a connection to any one of said lines, a sleeve relay operated upon the insertion of said plug in the jack of a subscribers line, a signaling circuit extending over the incoming end of said cord circuit, means effective when said relay is energized for reducing the potential of said signaling circuit, an assignment lamp, and a pair of relays in said'signaling circuit each upon energization adapted to cause the illumination of said lamp, one of said pair of relays responsive only to the normal potential of said signaling circuit.

11. In a telephone exchange system, subscribers lines, a cord circuit terminating in a plug terminal for extending a connection to any one of said lines, an assignment relay for causing the association of said cord circuit with apparatus common to the cord cir cuits of the operators position, a non-locking assignment key, a circuit for said relay under the control of said key, a self locking circuit for said relay independent of said key, and means for rendering the circuit of said relay ineffective it said plug terminal is up in the jack of one of said lines.

12. In a telephone exchange system, the method which comprises extending a calling line and seizing an idle connecting circuit in response to dialing impulses and in il luminating the lamp assigned to the selected connecting circuit regardless of whether the switching terminal of said connecting circuit is associated with a line with which it has previously established a connection.

In Witness whereof, I hereunto subscribe my name this 24 day of April A. D. 1920.

ALBEN E. LUNDELL.

In witness whereof, I hereunto subscribe my name this 26th day of April A. D. 1920.

EDGAR H. CLARK. 

